The study of tissue material takes place on a large scale for histological or pathological testing, such as for the purpose of making a diagnosis. Tissue is understood here to mean organic material isolated from, for instance, humans, animals or plants. For the purpose of studying the tissue material, the tissue material is cut into thin sections. By subsequently mounting the tissue cut into sections on slides, the tissue material can be studied under a microscope. However, such isolated tissue material comprises a substantial quantity of water. This makes cutting of the tissue material into sections difficult and increases the risk of undesirable variations in the thickness of the sections. There is also the risk during cutting of the tissue material into sections that the tissue material is compressed, thus reducing the reliability of the results of the study of the tissue.
In order to obviate the above stated drawbacks, it is known to pretreat the tissue material before it is cut into sections. Sample preparation prepares tissue specimens for sectioning, staining and diagnosis. The known paraffin processing method moves tissue specimens through a series of steps that comprise a fixation step aiming to preserve the tissue; a pretreatment step that removes water from the specimen by submersing it in, for instance, ethanol, clearing the tissue by contact with a clearing agent such as xylene, and infiltrating the tissue with paraffin wax; and an embedding step that allows orientation of the specimen in a block of paraffin or other moulding fluid. A final sectioning step using a microtome produces very thin sections from the block, which sections are positioned on a microscope slide for staining.
In the pretreatment step, the tissue material is placed in a container permeable to the relevant liquids and brought into contact with the different liquids. A known device for pretreating tissue material is described for instance in US 2011/0171088 A1. Such an apparatus (known in the art as a tissue processor) comprises a tissue treatment chamber connected to a number of containers for different pretreatment liquids such as alcohols, xylene and paraffin. Tissue material is arranged in a container permeable to the liquids and placed in the tissue treatment chamber, wherein the liquids flow sequentially through the tissue treatment chamber and the tissue material is brought into contact with these liquids.
For the purpose of embedding in a matrix material the pretreated tissue material infiltrated with paraffin, according to the known method, the tissue material is taken out of the permeable container and placed in a mould. A known mould here comprises a housing provided with a receiving space for the tissue material and an opening for placing the tissue into the receiving space. A known mould for embedding is described in WO 2009/152575 A1 and comprises, in addition to the housing and the receiving space, a container permeable to paraffin which functions as cover for the housing. After placing of the tissue material in the receiving space, the receiving space is closed with the cover or cassette and the whole is treated in a separate embedding device, which is likewise described in WO 2009/152575 A1. Following embedding of the mould, tissue material and cover in a matrix material, the mould is removed, wherein the cover remains to which is connected a projection in the form of the receiving space and comprising the tissue material. Diverse matrix materials are suitable for embedding purposes. The only prerequisite is that the matrix material can be brought from a first state, in which the matrix material is fluid for the purpose of embedding the tissue material through penetration of the matrix material into the tissue material, to a second state in which the matrix material is cuttable. A suitable matrix material is paraffin. In the cuttable state the tissue is cut into sections, mounted on a glass slide and the tissue material is ready to be studied. During cutting into sections, the embedded tissue material is secured with the cover in the microtome apparatus.
The above described known method for preparing tissue material is relatively labour-intensive and involves the risk of the tissue material being unnecessarily damaged during removal of the pretreated tissue material from the container and placing thereof in a mould. Tissue material can also be undesirably exchanged with tissue material from another container, thus reducing the reliability of the origin of the tissue material. It is further of great importance that the tissue material is placed in the correct orientation in the mould.
There is therefore a need for a method and device for preparing tissue material wherein the above stated drawbacks are at least partially obviated. An object of the present invention is to provide for the above stated need.